Evidence for Evolution

• Fossils

• Pentadactyl limb

• Embryology

• Biochemistry

• Classification

Fossils

Remains of organisms found in sedimentary rockTissues have been turned into minerals by means of pressure and temperatureOlder fossils are usually found deeper in the sedimentary rocks

(Parts of) Organisms are coveredby sediment, fossilise and arefound

Organisms living in water arefossilised more often

Fossilised skeleton of a mammoth

Fossilised fronts (leaves) of a fern

Fossilised human foot print Fossilised dinosaur foot print

Pentadactyl limb design

Competition in the seas and changing climatesmay have forced fishlike animals to adapt to living on landSwim bladders turned into lungs and fins into limbs

Fish

The body plan changed slowlyThe end result was a pentadactyl vertebrate, an Amphibian

Amphibians

Amphibians developed into Reptiles

Reptiles into Birds

And Mammals

The pentadactyl limb continued todevelop

The early horse was the size ofa dog. The animal lived in the Dense tropical forests and needed The four-toed foot for support on the soft soils.When the climate changed forestsdisappeared and the “horses”adapted. They lost toes and the bones in the remaining fingerbecame longer.A hoof protected the tip againstdamage.The horses had to be taller to see over the tall grass and able to run faster.

The present-day horse is four timestaller than its ancester.

Embryology

In the 19th century, Haeckel suggested that Embryology also supportsthe theory of evolution. Later however, it was discovered that he hadmanipulated his findings and diagrams

Haeckel’s hypothesis was that all Vertebrate animals undergo evolutionarysteps when they develop from a fertlised egg cell into a fully developedfoetus. He saw the above investigation as proof of his hypothesis.Scientists now only support parts of his idea.

Haeckel is also famous for his art work on marine animals.Below diagrams of Coelenterates, jelly fish and sea anemones

Biochemistry

The use of DNA, aerobic respiration and photosynthesis and many chemical recations are universal, used by many organisms

Classification shows the relationship between organisms and how they may have developed out of eachother

Theory of evolution

A young Darwin travelled to South America and gathereda large number of species.

After his return to England, hecontinued studying these specimenAnd he did several experimentson artificial selection of plants andAnimals

In 1859 Darwin published his theoryof evolution: Survival of the Fittest In his book: “On the Origin of Species”

• Darwin stated three rather obvious facts:

• - Species produce more offspring than needed for the continuation of the species

• - Offspring is not identical (variation)

• - There is not enough food/space for all individuals produced (survival of the fittest)

Species produce more offspring than needed for the continuation

of the species

Offspring is not identical (variation)

-There is not enough food/space for all individuals produced -(survival of the fittest)

Evolution based upon selection of the best variation in the offspring

Small variations won’t make a difference. The bigger de

difference however the more effect on the success of the

individual

Small differences changed the size and shape the beak of the ancesterThis happened in response to changes in the environment (availability ofAnd competition for food).Some birds remained general feeders others specialised

Speciation

• Mutation

• Variation

• Selection

• Speciation

• Evolution

Mutation

Variation (Lamarck)

Variation (Darwin)

Natural Selection

Sexual Selection

Speciation

Evolution